America’s Most Challenging High Schools ranks schools through an index invented by Washington Post education columnist Jay Mathews. The index formula is a simple ratio: the number of Advanced Placement, International Baccalaureate and Advanced International Certificate of Education tests given at a school in 2015, divided by the number of graduates that year. Noted in our national and local tables are the percentage of students eligible for government meal subsidies — a common benchmark for poverty — and each school’s average scores on the SAT, a common college entrance exam with a national average of 1497 out of 2400.

Mathews considers college test participation a better measure of school success than test scores, which largely reflect parental income. Schools with ratios of 1.000 or above make the list. The list has grown to include nearly 2,300 schools across the country and more than 180 in the Washington region. It includes some private schools - noted with a (P) - for comparison. Certain public schools with highly selective admissions are omitted from the list, but information about them can be found online, along with full local and national lists, at washingtonpost.com/highschoolchallenge.

Regional Rankings

The top 50 Washington-area schools, as ranked. The Washington Post's Jay Mathews. Principal schools are marked with a (p).